1. Field of the Invention
The present invention relates to a vehicle-use power generation control apparatus for controlling a power generating operation of a generator mounted on a vehicle such as a passenger car or a truck.
2. Description of Related Art
There is known a technique in which, in order to reduce variation of a rotational speed of a vehicle engine depending on its combustion cycle when the vehicle engine is in an idle state, a power generation torque control is performed such that an excitation current of a vehicle generator driven by the vehicle engine is decreased to decrease a power generation torque of the vehicle generator at the timing when the engine rotational speed decreases, and the excitation current is increased to increase the power generation torque of the vehicle generator at the timing when the engine rotational speed increases (refer to Japanese Patent Application Laid-open No. 58-217743, for example). There is known another technique in which, in order to reduce hunting in a cycle of 2 to 3 seconds of a vehicle generator due to its power generation torque when the vehicle engine is in its idle state, a value of the power generation torque is constantly calculated on the basis of an excitation current of the vehicle generator and a rotational speed of the vehicle generator, and the excitation current is limited so that an increasing rate of the power generation torque is kept below a certain value (refer to Japanese Patent Application Laid-open No. 2003-284257, for example).
The former technique as disclosed in Japanese Patent Application Laid-open No. 58-217743, in which decrease or increase of the excitation current is determined on the basis of only the timing of decrease or increase of the engine rotational speed, has a problem in that although the rotational speed variation of the vehicle engine can be suppressed, a variation of an output voltage of the vehicle generator cannot be prevent from becoming large, because this technique does not take the output voltage variation of the vehicle generator into account. This can causes overcharge or overdischarge of a vehicle battery charged by the vehicle generator.
The latter technique as disclosed in Japanese Patent Application Laid-open No. 2003-284257 has a problem in that although the idle speed variation of the vehicle engine can be suppressed if it is due to the power generation torque variation of the vehicle generator, it cannot be suppressed if it is due to factors other than the power generation torque variation of the vehicle generator.